The 3rd Generation Partnership Project (3GPP) has initiated the Long Term Evolution (LTE) program to bring new technology, new network architecture, new configurations, new applications and new services to wireless cellular networks in order to provide improved spectral efficiency and faster user experiences.
While the demands continue for greater functionality, low maintenance LTE systems, particularly in terms of network deployment and runtime service optimization, are also in demand.
The UTRAN architecture used prior to LTE, the 3GPP Universal Mobile Telecommunication System (UMTS) system, is shown in FIG. 1. The core network 100 communicates with the UTRAN 110 that consists of multiple radio network systems (RNS) 120. Each RNS consists of a radio network controller (RNC) 130 and one or more Node-Bs 135. The configurations and operations of the deployed Node-Bs 135 are totally controlled by the RNC 130 with explicit commands over the Iub link 140. Iub 140 is an RNC-to-Node-B interface that has been previously defined. The configurations and service upgrade of Node-Bs depend on the RNC and other cell engineering and planning efforts. Prior to LTE, no connections existed between UTRAN Node-Bs 135 and no requirements existed for self configuration and optimization. No means of self configuration and no defined procedures operating among Node-Bs existed.
In the new LTE network system, as illustrated in FIG. 2, the E-UTRAN architecture has been changed. The former RNC node no longer exists. The evolved-Node-Bs (eNBs) 200, 205 perform the radio access network functionality for E-UTRAN 210, are linked directly with the Core Network (EPC) 220, and are linked together among themselves. In the E-UTRAN, the new eNBs 200, 205 assume the RAN configuration, operation and management control functions as well as the radio interface configurations and operations. Furthermore, each new eNB such as 200, now interacts directly with the LTE Core Network 220 over the S1 interface as well as interacting with neighboring eNBs 205 over the X2 interface 240 and X2 connection control (X2C) interface (not shown) for handling wireless transmit/receive unit (WTRU) mobility management tasks on behalf of the new E-UTRAN.
When a newly deployed eNB 200, 205 powers up, it performs self configuration tasks, including operations over the X2C interface to interact with neighboring operational eNBs. This initial interaction is used to gather information, to certify the eNB and to enable configurations and cooperation as the eNB readies itself to enter E-UTRAN operational mode for serving the WTRUs in its coverage area.